Gargling with Listerine every day is a cheap and easy way to help control the spread of gonorrhoea, researchers find.
Photograph: Samuel Gibbs for the Guardian

Daily rinsing and gargling with a commercial brand of mouthwash could help control the spread of gonorrhoea, a study has found.

Researchers at a Melbourne clinic had noted more cases of gonorrhoea among men who had sex with men and sought to establish whether Listerine had an “inhibitory effect” against the bacteria that causes the infection.

They conducted a clinical trial involving 196 gay or bisexual men who had previously tested positive for gonorrhoea in their mouths and throat and were returning for treatment.

Of these, 58 tested positive for the bacteria in their throats on their return visits between May 2015 and February 2016.

The researchers split that group so that 33 men were randomly assigned to rinse and gargle with Listerine, and 25 did the same with a saline solution.

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Results showed the proportion of viable gonorrhoea in the throat was 52% after rinsing and gargling with Listerine for one minute, compared with 84% among the saline solution group.

The study, published in the journal Sexually Transmitted Infections, concluded: “Our data provides preliminary evidence to support the further investigation of mouthwash as a non-condom-based control measure for gonorrhoea.

“Listerine mouthwash is a cheap, easy to use and effective agent that inhibits gonorrhoea growth and requires further careful consideration and study.”

Researchers are conducting a larger trial to confirm the results and see whether the use of mouthwash could curb the spread of gonorrhoea. They must also establish how long the apparent effects of using the mouthwash lasted.

They said it was important to find a preventive measure that did not rely on condoms to ensure antibiotic-resistant strains of Neisseria gonnorhoeae did not develop.

According to the study, the manufacturer of Listerine claimed in 1879 that it could be used to cure gonorrhoea in the pre-antibiotic era, but no published scientific studies assessed the claim.

Gonorrhoea can be easily passed between people through unprotected vaginal, oral or anal sex, as well as sharing vibrators or other sex toys that have not been washed or covered with a new condom each time they are used.

About one in 10 infected men and almost half of infected women do not experience any symptoms.

The study was carried out by researchers from the Melbourne sexual health centre, Monash University faculty of medicine and the University of Melbourne microbiological diagnostic unit public health laboratory.